Magnetic transfer is a technique for transferring information, such as survo information, from a master medium to the magnetic recording layer of a magnetic recording medium (hereinafter referred to as a slave medium or a slave disk) placed in close contact with the master medium by applying a magnetic field to the disks. The master medium carries thereon a pattern of fine unevenness formed of a magnetic substance in accordance with information to be transferred such as survo signals. A known apparatus for carrying out magnetic transfer is disclosed in JP-A-11-25455.
FIG. 4 is a cross-sectional view of the magnetic transfer device of JP-A-11-25455. A vacuum pump 17 is operated with a valve 18 open to evacuate grooves 14 formed on a master disk 25. As a result, a slave disk 21 is brought into intimate contact with the patterned area of the master disk 25 by the atmospheric pressure 23. A magnetic field for magnetic transfer is applied to the disks in that state.
FIG. 5 is another known magnetic transfer apparatus featuring ensured vacuum contact. The apparatus has a pair of disk holders 35 and 36 each having suction holes 35b and 39b, respectively. A master disk 33 is fixed on the holder 35 by suction from a vacuum pump through an evacuation pipe 34 and the suction holes 35b. A slave disk 37 is superposed on the master disk 33 and fixed at the right position by suction through a pipe 38. Another master disk 39 is fixed on the other holder 39 by suction through an evacuation pipe 40 and the suction holes 39b. The holders 35 and 36 are joined together via an annular sealing member 42 to form a closed space therebetween. An elastic member 43 is provided as a buffer so as to allow the holders 35 and 36 to move in their axial direction by the amount of deformation. An O-ring 45 is seated on the sealing member 42 to seal the closed space. A slide sealing O-ring 44 is also seated on the sealing member 42 to seal the closed space.
According to JP-A-11-25455, however, a sufficient contact pressure is not obtained because of the absence of a holder for holding the master disk 25. The apparatus shown in FIG. 5 has difficulty in reducing the thickness of the holders 35 and 36. Besides, in the apparatus of FIG. 5, a magnet cannot approach the center of rotation because of the shafts 41 at the center of rotation.